Synthetic lubricating composition



United States Patent Ofifice 3,0fi9,357 Patented Dec. 18, 1962 3,069,357SYNTHETIC LUBRICATING COMPOSITION Ralph P. Cheslulr, Fishkill, andRaymond B. Tierney,

Wappingers Falls, N.Y., assignors to Texaco Inc., a corporation ofDelaware No Drawing. Filed Apr. 1, 1959, Ser. No. 803,367 Claims. (Cl.252-464) This invention relates to synthetic lubricant compositionscontaining extreme pressure additives which do not promote corrosiveproperties of the composition toward bearing metals such as copper andlead. More particularly the invention relates to ester-type lubricatingfluids containing additive amounts of metal halides complexed withsulfones and sulfoxides.

Lubricating requirements of high speed aircraft turbine engines makenecessary the use of lubricants possessing high extreme pressureproperties. Improved extreme pressure additives which do not degradeother lubricating properties are always in demand for these lubricants.

In accordance with the present invention, an improved lubricatingcomposition comprises an ester base lubricating fluid containing anadditive amount of the complexed reaction product of iron, cobalt ornickel chloride with a sulfone, disulfone or sulfoxide to increase theextreme pressure properties of the composition. The preferred reactionproduct is ferric chloride complexed with a disulfone. These reactionproducts are generally added to the lubricating fluid in amounts rangingfrom 0.05 to 2.0 (wt) percent and preferably from 0.1 to 1.0 (wt)percent.

Examples of complexed reaction products useful as E.P. additives forthis invention include: ferric chloride-npropyl sulfone, ferricchloride-n-propyl disulfone, ferric chloride-butyl sulfoxide, ferricchloride-disulfone, of his (Z-ethylhexyl thiocarbityl) ether, ferricchloride-sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether, ferricchloridedisulfone of bis(3-thia-6-oxa-8-ethyldodecyl) ether, cobaltchloride-n-amyl disulfone, cobalt chloride-sulfoxide ofbis(3-thia-6-oxa-8-ethyldodecyl) ether, cobalt, chloridedisulfone ofbis(3-thia-6-oxa-8-ethyldodecyl) ether, nickel chloride-n-propylsulfone, nickel chloride-n-butyl sulfoxide, nickel chloride-disulfone ofbis(2-ethylhexyl thiocarbityl) ether, nickel chloride-sulfcxide ofbis(3-thia-6- oxa-8-ethyldodecyl) ether and nickel chloride-disulfone ofbis(3-thia-6-oxa-8-ethy1 dodecyl) ether.

In general, aliphatic esters of aliphatic dicarboxylic acids are used asbase fluids in the lubricants of this invention. The dicarboxylic acidcomponent is usually an aliphatic dicarboxylic acid containing 6 to 12carbon atoms but glutaric acid esters and succinc acid esters may alsobe used. From the standpoint of cost and availability, the preferreddibasic acids are adipic acid, 'sebacic acid and azelaic acid.

The aliphatic alcohols used to form the diesters usually contain atleast 4 carbon atoms and may contain 20 or more carbon atoms. C to Calcohols are most commonly used. Ether alcohols, such as Cellosolve andCarbitol may also be used in the formation of the aliphatic diesters oforganic dicarboxylic acids used as the lubricating base in thecompositions of this invention.

Specific examples of the dialkyl esters of aliphatic dicarboxylic acids,which are the preferred base fluids for use in the lubricant compositionof the invention, are as follows: di-isooctyl azelate, di-Z-ethylhexylsebacate, di- 2-ethyl hexyl azelate, di-Z-ethylhexyl adipate, dilaurylazelate, di-sec-amyl sebacate, di-Z-ethylhexyl alkenylsuccinate,di-2-ethoxyethyl sebacate, di-2-(2'methoxyethoxy) ethyl sebacate,di-Z-(Zethylbutoxy) ethyl sebacate, di-Z- butoxyethyl azelate,di-2-(2'butoxyethoxy) ethyl alkenylsuccinate, etc.

In addition to the aliphatic dicarboxylic acid esters described above,polyester lubricants formed by a reaction of an aliphatic dicarboxylicacid, a glycol and a monofunctionai compound, which is either analiphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, inspecified mol ratios are also employed as the synthetic lubricating basein the compositions of this invention; polyesters of this type aredescribed in US. 2,628,974 to Robert T. Sanderson, issued February 17,1953. Complex esters formed by reaction of a mixture containingspecified amounts of 2-ethyl-l,3-hexanediol, sebacic acid andZ-ethylhexanol and by reaction of a mixture containing adipic acid,diethylene glycol and 2-ethylhexanoic acid illustrate this class ofsynthetic polyester lubricating bases.

Polyesters formed by reaction of a monocarboxylic acid and a glycol mayalso be used as the ester component. The acid component is usually analiphatic acid containing at least 6 carbon atoms. The glycol componentis advantageously a straight glycol such as 1,6-l1exanediol, but etherglycols, such as tetraethylene glycol, may also be used.

Specific examples of the diesters of glycols are the following:di-n-decanoate of 1,4-butanediol, di-Z-ethylhexanoate of 1,6-hexanediol,dilaurate of 1,4-hexanediol, dioctanoate of 1,5-pentanediol, dilaurateof tetraethylene glycol, dilaurate of triethylene glycol, dioctanoate ofpentaethylene glycol.

Complex esters formed by reacting trimethylol alkanes with various molratios of dibasic acids and monobasic acids or alcohols is anotherexample of polyesters useful for the base fluid of the lubricants ofthis invention.

The sulfur analogs of the above-described esters are also used in theformulation of the lubricating compositions of this invention.Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate, di-n-octylthioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs ofpolyesters are exemplified by the reaction product of adipic acid,thioglycol and Z-ethylhexyl mercaptan.

The finished lubricant composition of this invention normally containsother well known additives which act as V.I. improvers andanti-oxidants. For example, phenothiazine, which acts as an anti-oxidantand a methacrylate polymer, which acts as a V1. improver, thickener, anddetergent, are usually included in the finished lubricants and are oftennecessary in order to meet rigid military requirements. Phenothiazine,which has the formula:

is a particularly effective anti-oxidant and anti-corrosive agent. Itinhibits corrosion by preventing oxidation of the components of thelubricating composition to acidic bodies which are inherently corrosive.Phenothiazine is usually present in a concentration of 0.1 to 1.5 weightpercent of the lubricant composition.

Various aromatic amines either alone or in combination are also known tohave anti-oxidant properties and may at times be used in the presentcomposition. For example, naphthylarnines, diphenylamines and phenylenea diamines in amounts up to about 2 percent by weight are veryefiective.

Methacrylate polymers are well known V.I. improvers and pour pointdepressors. Polyester base lubricants, although they, per se, possessexcellent V.l. and pour, usually require the presence of smallconcentrations of methacrylate polymers to meet the requirements ofmilitary specifications. These methacrylate polymers are usuaccess? allycopolymers of two or more esters of methacrylic acid and usually have amolecular weight between 500 and 20,000. The methacrylate esters havethe following general formula:

wherein R is an aliphatic radical preferably ranging from butyl tostearyl.

Copolymers which find particular use as Vi improvers and pour pointdepressants are the following: a copolymer wherein R in the aboveformula comprises 20% lauryl, 40% octyl and 40% cetyl; a copolymerwherein R in the above formula is 50% stearyl and 50% lauryl; acopolymer wherein R in the above formula comprises 50% lauryl and 50%octyl.

=Methacrylate polymers are usually sold in the form of a concentratecomprising approximately 60 to 40% polymer in a carrier oil. For thelubricant compositions of this invention, it has been found advisable touse an ester-type carrier oil rather than the usual mineral baselubricating oil. The use of a methacrylate ester in an ester-typecarrier oil has proven particularly effective in meeting the lowtemperature requirements of military specifications.

Methacrylate polymers can constitute 1 to 20 weight percent of thecomposition but ordinarily are used in a concentration between 1.5 and10 weight percent.

In general the complexed products of this invention are conventionallyformed by mixing or refluxing equal mols of the sulfone, disulfone orsulfoxide component with the metal halide component until the reactionis complete.

The following examples demonstrate the preparation of some of thecomplexed reaction products of this invention.

EXAMPLE I 450 g. of bis(3-thia-6-oxa-8-ethyldodecyl) ether and 300 ml.of acetic acid were placed into a 2 liter flask and heated to 90 C. 38g. of 30 percent hydrogen peroxide were then added to the mixture over a30 minute period. The 90 C. temperature was maintained for 40 minutesafter which 38 g. of hydrogen peroxide in 40 ml. of acetic acid wereadded over a 30 minute period. Again after maintaining the sametemperature for 40 minutes, 40 g. of hydrogen peroxide in 40 ml. ofacetic acid were added over a 30 minute period. The resulting mixturewas kept at a temperature of 95-100 C. for 2 /2 hours and then allowedto stand overnight. The mixture was then shaken with 2 liters of waterto form an emulsion. The emulsion was ether extracted, washed with 1liter of 5 percent sodium bicarbonate, and then water washed untilneutral to Congo red. The ether was removed and toluene added forremoval of water. The mixture was distilled off until the pottemperature reached 86 C./5 mm. 453 g. of a clear amber liquid fluid wasobtained having a refractive index at 20 C. of 1.4798. The product, thesulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether, in the amount of 96g. and 115 g. of cobalt chloride in 500 ml. of benzene were added to aone-liter flask and refluxed for 6 hours. 41 ml. of water separated andthe reaction mixture was blue in color. The mixture was allowed to standover night and then filtered. 71 g. of solid material, be lieved to be'CoCl was recovered and benzene was stripped from the filtrate. Theproduct was dark blue, very viscous and weighed 95 g. Analysis showed8.92 percent cobalt and 9.90 percent sulfur. This material, cobaltchloride-sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether complex wasadded to an estertype synthetic base fluid for testing. The testcomposition was as follows:

(Wt.) percen Di-Z-ethylhexyl sebacate 79.5 Copolymer of stearyl andlauryl methacrylate in di- Z-ethylhexyl sebacate (50% cone.) 20.0 Ferricchloride-sulfoxide complex 0.5

Tests on the above composition gave the following results:

The above results demonstrate that the synthetic lubricant compositionof the invention are excellent in stability and resistance to oxidationand corrosion. This is particular.y evident with respect to copper whichis an important bearing metal.

The following is another example of the preparation of a complexedreaction product of this invention:

EXAMPLE II 3 liters (2832 g.) of bis(3-thia-6-oxa-S-ethyldodecyl) etherand 750 ms. of 50% H were poured into a 12 liter, three neck flask. Themixture was heated to 70 C. by heating mantle and then a hot solution of375 g. of KMnO dissolved in 3750 ml. of water was added at a rate sothat the temperature was maintained between 7075 C. Addition required 3%hours and thereafter solid potassium permanganate was slowly added attemperatures between 70-75 C. When the brown color of the mixture becameconstant for 1 hour at 75 C. the temperature was raised to C. This wasmaintained for one hour and the color remained constant. The mixture wasallowed to cool and 376 g. of solid KMnO was added. On standing an oillayer separated from an aqueous layer and the dark brown aqueous layerwas extracted with 2500 mls. of ether. The ether was stripped and theoil was treated with toluene for removal of water. It was then filteredand allowed to stand. The oil layer was then treated with charcoal andfiltered. The resulting product, the disulfone ofbis(3-thia-6-oxa-8-ethyldodecyl) ether, weighed 2256 g., contained 11.9percent oxygen, 11.84 percent sulfur, had a hydroxyl number of 23, and aneutralization number of 0.6.

200 g. of the above disulfone was placed in a 500 ml. flask and stirred.40 g. of ferric chloride was added slowly at room temperature during thestirring temperature of the reaction mixture was raised to 65 C. for 1hour and then allowed to cool to room temperature. The product wasfiltered and the filtrate weighed 235 g. 50 g. of this filtrate wasslurried with 300 mls. of water at C. for 1 hour and then cooled to roomtemperature. An oil layer separated and the water layer was ex-- tractedwith n-pentane. The pentane was stripped and. toluene added for waterremoval. The FeCl -disulfone. complex produced weighed 31 g.

The reaction products of this invention were tested for extreme pressureproperties in the well-known Mean Hertz Load Test which briefly consistsof applying the lubricant to three locked steel balls and a fourth steelball which is made to rotate against the locked balls at predeterminedpressures. The performance of the lubricant, as determined by knownstandards, is measured and is termed the Mean Hertz load for thatparticular lubricant composition. This test is more fully described inUS. 2,600,058.

Data for various lubricant compositions, including those of theinvention, in the Mean Hertz Load Test are set forth in the followingtable:

Table I MEAN HERTZ LOAD TEST Composition: M.H.L. value. Base fluid A 121 Base fluid A+0.5 (wt) percent of CoCl sulfoxide of bis(3-thia-6-oxa-8-ethyldodecyl) ether 2 Base fluid B 2 21 Base fluid B+0.5(WL) percent dibutyl sulfone 22 Base fluid B+0.5 (WL) percent FeCl-n-propyl sulfone Base fluid 21 Base fluid C+1.0 (wt) percent Fecl-disulfone of bis (3-thia-6-oxa-8-ethyidodecyl) ether 52 1Di2-ethy1hexy1 sebacate (wt) percent of 50 percent solution of thecopolymer of lauryl and stearyl methacrylates in di-Z-ethyihexylsebacate+0.5 twt.) percent phenothiazine. Di-2-et11ylhe. :y1 azelate+18(Wt) percent of 40 percent solution of the polymer of butyl methacrylatein di-2-ethy1- hexyl sebacate+ 0.5 (wt) percent phenothiazine.

Di-2-etl1y1l1exyi aze1ate+0.5 (Wt) percent phenothiazine. From the abovedata, it is obvious that the complexed products of this invention aresuperior E.P. agents for ester-type synthetic lubricants. Thesuperiority of the complexed sulfones and sulfoxides over the normalsulfones, such as the dibutyl sulfone of the table is also evident sincethe dibutyl sulfone does not increase the extreme pressure properties ofthe base fluid significantly.

Obviously, many modifications and variations of the invention ashereinabove set forth may be made without departing from the spirit andscope thereof, and therefore, only such limitations should be made asare indicated in the appended claims.

We claim: 1. A synthetic lubricant consisting essentially of an esterbase lubricating fluid and from 0.05 to 0.2 weight percent of thecomplex formed by the reaction of about 6 1 part by weight of a chlorideof a metal selected from the group consisting of iron, cobalt and nickelwith from about 0.8 to 5.0 parts by weight of a compound selected fromthe group consisting of sulfones, disulfones and sulfoxides, said amountbeing sufficient to incrase the extreme pressure property of thecomposition.

2. A synthetic lubricating composition consisting essentially of a majoramount of aliphatic ester of an aliphatic dicarboxylic acid and from0.05 to 0.2 weight percent of the complex formed by the reaction ofabout 1 part by Weight of a chloride of a metal selected from the groupconsisting of iron, cobalt and nickel with from about 0.8 to 5.0 partsby weight of a compound selected from the group consisting of sulfones,disulfones and sulfoxides.

3. A synthetic lubricating composition as described in claim 2 whereinthe complex is formed by reaction of ferric chloride andn-propylsulfone.

4. A synthetic lubricating composition as described in claim 2 whereinthe complex is formed by reaction of ferric chloride and the sulfoxideof his (3-thia-6-oxa-8 ethyldodecyl) ether.

5. A synthetic lubricating composition as described in claim 2 whereinthe complex is formed by reaction of ferric chloride and the disulfoneof his (3-thia-6-oxa-8- ethyldodecyl) ether.

References Cited in the file of this patent UNITED STATES PATENTS2,199,944 Peski et al. May 7, 1940 2,257,969 Loane et al Oct. 7, 19412,318,629 Prutton May 11, 1943 2,645,613 Adelson et al July 14. 1953OTHER REFERENCES Lub. Eng, August 1952, pp. 177-179. I. and E. Chem.,April 1947, vol. 39, No. 4, pp. 494 and 495.

1. A SYNTHETIC LUBRICANT CONSISTING ESSENTIALLY OF AN ESTER BASELUBRICATING FLUID AND FROM 0.05 TO 0.2 WEIGHT PERCENT OF THE COMPLEXFORMED BY THE REACTION OF ABOUT 1 PART BY WEIGHT OF A CHLORIDE OF AMETAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT AND NICKEL WITHFROM ABOUT 0.8 TO 5.0 PARTS BY WEIGHT OF A COMPOUND SELECTED FROM THEGROUP CONSISTING OF SULFONES, DISULFONES AND SULFOXIDES, SAID AMOUNTBEING SUFFICIENT TO INCRASE THE EXTREME PRESSURE PROPERTY OF THECOMPOSITION.